A single class of drug is at the center of the deaths: opioids. While some of these drugs are legal and frequently prescribed by doctors for pain relief, they can also be addictive in ways similar to illegal opioids like heroin.

Centers for Disease Control and Prevention

Between 2010 and 2015, efforts aimed at getting doctors to reduce their prescription of legal opioids appeared to be linked with a slight slow-down of deaths involving some drugs. But over the same time period, deaths involving heroin tripled. Similarly, deaths involving drugs like fentanyl and tramadol also rose, highlighting the efforts that are still needed to address the crisis.